A GLOBALLY significant Viking treasure hoard has been unearthed by a father and son using metal detectors.

David Whelan and his son, Andrew, stumbled on the hoard, in the Harrogate area, in January.

Experts describe the treasure, which includes 617 silver coins, a gold arm-ring and a gilt silver vessel, as Britain's most important Viking find in 150 years.

The "Harrogate Hoard" -believed to have been looted from a monastery -was probably buried after the invasion of the Viking kingdom of Northumbria, in 927AD, by Anglo-Saxon king Athlelstan.

The hoard has yet to be valued, but is estimated to be worth more than £750,000.

The Treasure Act states the Whelans are entitled to half its value, while the owner of the land where it was unearthed will receive the other half.

The pair kept the find intact and reported it. It was then transferred to the British Museum, where conservators carefully excavated each find to avoid damaging the objects.

Rare and previously unseen coins are among those discovered, and will provide valuable clues about England's history in the early Tenth Century and Yorkshire's wider cultural contacts in the period. The booty was collected from Afghanistan, Ireland, Russia, Scandinavia and continental Europe.

David Whelan, 60, from Leeds, said: "It was a muddy January morning. We were in a muddy field digging down. We got some lead out and some more lead and this round ball covered in mud.

"I could see these bits of silver on the top and the coin stuck in it, so I called Andrew back. We got all the bits out and made sure we had everything and went home to decide what to do with it."

He joked: "It will be worth a sizeable sum -if only I had been out there on my own, I would have got twice as much."

Andrew Whelan, 35, said: "There have been a number of stunning finds. It could be anybody in any field that finds it. It is a hobby anyone could take up."

At a treasure trove inquest in Harrogate yesterday, Coroner Geoff Fell declared the hoard treasure.

He said: "I am delighted that such an important Viking hoard has been discovered in North Yorkshire. We are extremely proud of our Viking heritage in this area.

"This is of international significance. I am still intrigued as to how it ended up where it did.

The treasure will be valued by the Independent Treasure Valuation Committee.

The British Museum, York Museum Trust and Harrogate Borough Council's Museums and Arts Service will try to raise money to buy the pieces and put them on show.